Low profile outboard with in-line engine

ABSTRACT

An outboard motor comprising a propulsion unit adapted to be attached to the transom of a boat for vertical swinging movement relative to the transom about a horizontal tilt axis and for steering movement relative to the transom about a steering axis extending transversely of the tilt axis. The propulsion unit comprises a lower unit including an exhaust gas discharge outlet normally located underwater, a powerhead assembly rigidly fixed to the top of the lower unit and including an engine with a plurality of vertically in-line cylinders each including an exhaust port, together with an exhaust gas discharge system including an inverted &#39;&#39;&#39;&#39;U&#39;&#39;&#39;&#39; shaped passageway comprising an upper junction portion located above the at-rest water level when the outboard motor is boat mounted, a first leg extending downwardly from the junction portion and communicating with at least one of the exhaust ports, and a second leg extending downwardly from the junction portion and separately from the first leg and communicating with the lower unit underwater exhaust gas discharge outlet. Also included in the disclosed outboard motor is an upwardly open water guard which extends upwardly from above the lower unit, in watertight encircling relation to the engine, to above the at-rest water level.

I Umted States Patent 1191 111] 3,91 1,853

Strang Oct. 14, 1975 LOW PROFILE OUTBOARD WITH [N-LINE ABSTRACT ENGINE An outboard motor comprising a propulsion unit 75 Inventor; Charles stung, Lake Forest, 1. adapted to be attached to the transom of a boat for 0 vertical swinging movement relative to the transom AS51811: Outboard Manne m about a horizontal tilt axis and for steering movement waukegan relative to the transom about a steering axis extending [221' Filed: Apr. 11, 1974 transversely of the tilt axis. The propulsion unit comprises a lower unit including an exhaust gas discharge [21] Appl' 459310 outlet normally located underwater, a powerhead as- Related 5. Application Data sembly rigidly fixed to the top of the lower unit and [63] Continuation of Ser. No. 330,596, Feb. 8, 1973, l an engine i apluramy vertically in'line abandoned. cylmders each mcludmg an exhaust port, together with an exhaust gas discharge system including an in- 52 us. c1 115/18 R vetted Shaped passageway comPrising an upper 51 Int. c1. B63H 5/13 junction P" located above the at-rest Water level [58] new of Search 115/12 R 17, 18 123/1 when the outboard motor is boat mounted, a first leg 123/195 P extendlng downwardly from the junctlon portion and communicating with at least one of the exhaust ports, [56] References Cited and a second leg extendinlg downwardly frlom th(el junction portion an separatey rom t e 1rst eg an com- S STATES PATENTS v municating with the lower unit underwater exhaust gas 2,209,301 '7/1940 Johnson et al. 123/195 P discharge outlet. Also included in the disclosed 222g? 1 4 board motor is an upwardly open-water guard which 2718866 9/1955 'g 5/1 8 R extends upwardly from above the lower umt, in wateret m R encircllng relatlon to the engine, t0 above the at- 3,577,952 5/1971 Tado 115/17 rest Water level- 3,599,594 8/1971 Taipale 115/17 Primary ExaminerTrygve M. Blix Assistant Examiner-Jesus D. Sotelo Attorney, Agent, or Firm-Michael, Best & Friedrich 9 Claims, 2 Drawing Figures U.S. Patent Oct. 14, 1975 lllilllllllll" '0 I- ll LOW PROFILE OUTBOARD WITH IN-LINE ENGINE This application is a continuation of my application Ser. No. 330,596 filed Feb. 8, 1973 now abandoned.

BACKGROUND OF THE INVENTION The invention relates generally to outboard motors and particularly to outboard motors including multicylinder engines. The invention has particular significance to in-line engines including four or more cylinders, but is not limited to such in-line engines.

In conventional commercial construction, as illustrated in FIG. I, the engine or powerhead 11 of an outboard motor 13 is rigidly attached to the upper end of a drive shaft housing 15 which normally extends from above to below a swivel bracket 17 and which, at its lower end, is rigidly connected to a lower unit 19 carrying a propeller 21. The drive shaft housing 15 is normally connected to the swivel bracket 17 for steering movement relative thereto through a king pin 23 which is pivotally carried by the swivel bracket 17 and con nected to the drive shaft housing 15 through suitable vibration isolating mounts. Exhaust gas from the exhaust ports 24 of the engine combustion chambers or cylinders is directed through a downwardly open vertically extending exhaust passage 26 and through the drive shaft housing 15 to an underwater discharge outlet 25.

This prior construction results in location of the powerhead about 15 to 20 inches above the at-rest water level and advantageously serves to keep water out of the engine cylinder exhaust ports and carburetor inlets. However, this construction also suffers from the disadvantages of a high center of gravity and an ungainly appearance.

Attention is also directed to the prior Holterman US. Pat. No. 3,613,631, issued Oct. 19, 1971.

SUMMARY OF THE INVENTION The invention provides a low profile, low center of gravity outboard motor including a multi-cylinder engine. More particularly in accordance with the invention. there is provided a propulsion unit in which the lowermost combustion chamber or cylinder in the powerhead is located adjacent to or below the at-rest water level when the outboard motor is boat mounted (and preferably below the at-rest water level) together with an exhaust gas discharge system which includes an inverted U shaped passageway with a junction portion located above the normal at-rest water level when the outboard motor is boat mounted (and preferably substantially above). The inverted U shaped passageway further includes a first leg extending downwardly from the junction portion and communicating with the exhaust ports and a second leg communicating with the junction portion separately from the first leg and extending downwardly and in communication with and underwater exhaust gas discharge outlet.

Also in accordance with the invention there is provided a bucket or water guard which extends upwardly from adjacent the bottom of the powerhead in watertight, encircling relation to the powerhead to above (and preferably substantially above) the at-rest water level when the outboard motor is boat mounted.

Thus in accordance with the invention, even though the powerhead is located relatively low, entry of water into the engine exhaust ports or into the carburetor air inlets is prevented by one or both of the water guards and the inverted U shaped exhaust gas discharge passageway.

One of the principal objects of the invention is the provision of a low profile and low center of gravity outboard motor having a multi-cylinder in-line engine.

Another of the principal objects of the invention is the provision of an outboard motor engine which is supported at a substantially lower level than heretofore and which includes means for preventing entry of water into the engine notwithstanding its relatively low position. 1

Another of the principal objects of the invention is the provision of an outboard motor which includes an engine supported at a substantially lower level than heretofore and which further includes a water guard in encircling, watertight relation to the engine.

Another of the principal objects of the invention is the provision of an outboard motor which includes an engine supported at a substantially lower level than heretofore and which further includes means for preventing entry of water into the engine exhaust ports through the exhaust gas system.

Other objects and advantages of the invention will become known by reference to the following description. claims and drawings.

THE DRAWINGS FIG. 1 is a side elevational view, partially in section, of a prior art outboard motor.

FIG. 2 is a side elevational view, partially in section, of an outboard motor embodying various of the features of the invention.

Before explaining the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts set forth in the following general description or illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

GENERAL DESCRIPTION Shown in FIG. 2 is an outboard motor 31 which is attached to the transom 33 of a boat 35. The line 37 indicates the at-rest water level or line relative to the boat 35 and motor 31. Of course, the waterline is subject to vertical fluctuation in response to wave motion, etc.

The outboard motor 31 includes a propulsion unit 39 and means connected to the propulsion unit and adapted to be attached to the boat transom 33 for affording vertical swinging movement of the propulsion unit 39 relative to the transom 33 about a horizontal tilt axis 41 and for affording steering movement of the propulsion unit 39 relative to the transom 33 about a steering axis 43 extending transversely of the tilt axis 41. In the illustrated construction, such means comprises a transom bracket 45 adapted to be attached to the boat hull 35, together with a swivel bracket 47 pivotally connected to the transom bracket 45 about the horizontal tilt axis 41. In turn, the propulsion unit 39 is pivotally connected to the swivel bracket 47 for common vertical swinging movement with the swivel bracket relative to the transom bracket 45 and for horizontal swinging movement relative to the swivel bracket 47 about the steering axis 43 provided by a king pin 49 extending transversely of the tilt axis 41.

The propulsion unit 39 comprises a conventional lower unit 51 including a cavitation plate 53, a rotatably mounted propeller 55, and an underwater exhaust gas discharge outlet 57 which, in the illustrated construction, is provided in the propeller 55. Alternatively, the outlet 57 could be provided elsewhere in the lower unit.

In accordance with the invention, there is rigidly connected to the lower unit 51 a powerhead assembly or engine 61 including an engine block and associated equipment, as for instance one or more carburetors. In the illustrated construction, the engine 61 includes four in-line combustion chambers or cylinders 67, each including one or more exhaust ports 69, all of which ports are generally vertically aligned. In addition, the illustrated engine 61 has associated therewith two vertically spaced carburetors 63, each including an air inlet 71.

While the powerhead assembly or engine 61 can be rigidly mounted directly to the lower unit 51, in the illustrated construction, there is rigidly fixed between the powerhead assembly or engine 61 and the lower unit 51 a relatively thin adaptor plate 75 which includes an exhaust passage 77 communicating with an exhaust passage 78 which is located in the lower unit 51 and which terminates at the exhaust gas discharge outlet 57 at the rear of the propeller 55. Extending forwardly from the adaptor plate 75 is a bracket 79 which is connected to the lower end of the king pin 49.

As can be readily appreciated from FIG. 2, the lower most of the combustion chambers or cylinders 67 is substantially entirely below the at-rest water level and the lower one of the carburetors 63, as well as the second from the bottom one of the cylinders 67 are located only slightly above normal at-rest water level, and in the absence of any protective means, would be subject to immersion in water.

Accordingly, as the lower cylinders 67 and the lower carburetor 63 are located adjacent to or below the atrest water level, in accordance with the invention, means are provided for preventing immersion of the lower part of the engine 61 in water and for preventing entry of water into the engine 61 through the exhaust gas ports 69.

While various arrangements can be employed to prevent at least partial immersion of the engine 61 in the water, in the illustrated construction, there is provided an upwardly open water guard or bucket 81 including a bottom wall 83 rigidly sandwiched between the adaptor plate 75 and the powerhead 61. The water guard 81 also includes a nonapertured continuously extending tubular portion or housing portion 85 which extends upwardly from the bottom wall 83 in watertight encircling relation to the engine or powerhead assembly 61 to a level above the at-rest level, and preferably substantially above the at-rest water level, so as to thereby provide a dam which prevents water from reaching the engine 61 even though a portion of the engine is located below the at-rest water level and even though there is vertical variation in the at-rest water level due to wave motion.

At its upper end, the water guard 81 is adapted to removably receive an engine cover 87.

As shown in FIG. 2, the upper end of the king pin 49 is connected directly to the powerhead assembly or engine 61 by a bracket 91 extending through a slot or aperture 93 in the water guard 81. In this regard, there is also provided a boot or seal 95 which extends between the bracket 91 and the water guard 81 to prevent entry of water.

If desired, the water guard 81 could be non-slotted and the bracket 91 could extend directly from the water guard 81 to the king pin 49 as the water guard 81 extends rigidly from the connection of the engine 61 to the lower unit 51.

Referring to the lower bracket 79, the adaptor plate 75 could be omitted (with the engine 61 being directly converted to the lower unit 51) and the lower bracket 79 could extend directly from the powerhead assembly or engine 61 through a slot (not shown) in the water guard 81 with a suitable watertight seal or boot (not shown) interposed between the bracket 79 and the water guard 81. Under such circumstances the bottom of the water guard 81 would be sandwiched directly between the lower unit 51 and the powerhead assembly or engine 61.

Furthermore, the water guard 81 need not include the bottom wall 83 so long as the lower end of the water guard 81 is suitably attached in watertight relation to the lower unit 51, or to an adaptor, such as the adaptor plate 75, or to a bottom portion of the powerhead assembly or engine 61, in such manner as to prevent entry of water through the mounting.

Suitable vibration isolators (not shown) can be utilized between the king pin 49 and the powerhead assembly or engine 61 so as to reduce noise and vibration transmission from the engine 61 to the king pin 49 and thence to the boat hull 35.

Entry of water into the lower engine cylinders 67 through the exhaust ports 69 is prevented, in accordance with the invention, by valveless means in the form of an inverted U" shaped exhaust passageway 101 which includes an upper junction portion 103 located above, and preferably substantially above, the atrest waterline. Extending downwardly from the junction portion 103, is a first passageway leg 105 which communicates with the exhaust ports 69 of the lower cylinders 67. The leg 105 can also extend above the junction portion 103 to communicate with the exhaust ports 69 of the upper cylinder 67. Also extending downwardly from the junction portion 103, and separately from the first leg 105, is a second passageway leg 107 which communicates through the exhaust passage 77 on the adaptor plate 75 with the exhaust passage 78 in the lower unit 51 and with the exhaust discharge outlet 55. Thus, water entering into the exhaust system can enter into the exhaust ports 69 only by overflowing through the relatively elevated junction portion 103 of the exhaust passageway 101. As this junction portion 103 is located above the at-rest water level, entry of water into the engine 61 through the cylinder exhaust ports 69 from the exhaust gas discharge system is normally prevented.

Various of the features of the invention are set forth in the following claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An outboard motor comprising a propulsion unit, means connected to said propulsion unit and adapted to be attached to the transom of a boat for affording vertical swinging movement of said propulsion unit relative to the transom about a horizontal tilt axis and for affording steering movement of said propulsion unit relative to the transom about a steering axis extending transversely of said tilt axis, said propulsion unit comprising a lower unit including an exhaust gas discharge outlet normally located underwater, a powerhead assembly rigidly fixed to the top of said lower unit and including an engine with a plurality of vertically in-line cylinders each including an exhaust port, and an exhaust gas discharge system including an inverted U- shaped passageway comprising an upper junction portion located above the at-rest water level when the outboard motor is boat mounted, a first leg extending downwardly from said junction portion and communicating with at least one of said exhaust ports, and a second leg extending downwardly from said junction portion and separately from said first leg and communicating with said lower unit underwater exhaust gas discharge outlet.

2. An outboard motor comprising a transom bracket adapted to be attached to the transom of a boat, a swivel bracket adapted to be connected to said transom bracket for vertical swinging movement about a horizontal tilt axis, a propulsion unit connected to said swivel bracket for common vertical swinging movement relative to said transom bracket and for steering movement relative to said swivel bracket about a steering axis extending transversely of said tilt axis, said propulsion unit comprising a lower unit including an exhaust gas discharge outlet normally located underwater, a powerhead rigidly fixed to the top of said lower unit and including an engine with a plurality of vertically in-line cylinders each including an exhaust port .and with the lowermost of said exhaust ports being located adjacent to or below the at-rest water level when the outboard motor is boat mounted, a water guard extending upwardly from the bottom of said powerhead in watertight encircling relation to said powerhead to above the at-rest water level when the outboard motor is boat mounted, and an exhaust gas discharge system including an inverted U shaped passageway comprising an upper junction portion located above the at-rest water level when the outboard motor is boat mounted, a first leg extending downwardly from said junction portion and communicating with at least one of said exhaust ports, and a second leg extending downwardly from said junction separately from said first leg and communicating with said lower unit underwater exhaust gas discharge outlet.

3. An outboard motor comprising a propulsion unit, means connected to said propulsion unit and adapted to be attached to the transom of a boat for affording vertical swinging movement of said propulsion unit relative to the transom about a horizontal tilt axis and for affording steering movement of said propulsion unit relative to the transom about a steering axis extending transversely of said tilt axis, said propulsion unit comprising a lower unit including an exhaust gas discharge outlet normally located underwater, a powerhead assembly rigidly fixed to the top of said lower unit and including an engine with a plurality of combustion chambers each including an exhaust port, and an exhaust gas discharge system communicating between said exhaust ports and said exhaust gas discharge outlet and including an inverted U-shaped portion preventing entry of water through said exhaust gas discharge system into said combustion chambers under normal conditions.

4. An outboard motor comprising a propulsion unit, means connected to said propulsion unit and adapted to be attached to the transom of a boat for affording vertical swinging movement of said propulsion unit relative to the transom about a horizontal tilt axis and for affording steering movement of said propulsion unit relative to the transom about a steering axis extending transversely ofsaid tilt axis, said propulsion unit comprising a lower unit including an exhaust gas discharge outlet normally located underwater, a powerhead assembly rigidly fixed to the top of said lower unit and including an engine with a plurality of combustion chambers each including an exhaust port, and an exhaust gas discharge system communicating between said exhaust ports and said exhaust gas discharge outlet and including valveless means located upstream of said exhaust gas discharge outlet for preventing entry of water through said exhaust gas discharge system into said combustion chambers.

5. An outboard motor comprising a propulsion unit, means connected to said propulsion unit and adapted to be attached to the transom of a boat for affording vertical swinging movement of said propulsion unit relative to the transom about a horizontal tilt axis and for affording steering movement of said propulsionunit relative to the transom about a steering axis extending transversely of said tilt axis, said propulsion unit comprising a lower unit including an exhaust gas discharge outlet normally located underwater, a powerhead rigidly fixed to the top of said lower unit and including an engine with a plurality of combustion chambers each including an exhaust port with the lowermost of said exhaust ports being located adjacent to or below the at-rest water level when the outboard motor is boat mounted, an exhaust gas passageway communicating between said exhaust ports and said exhaust gas discharge outlet and including an inverted U-shaped portion preventing entry of water through said passageway and said ports into said combustion chambers, and a water guard extending upwardly from the bottom of said powerhead in watertight encircling relation to said powerhead to above the at-rest water level when the outboard motor is boat mounted.

6 An outboard motor comprising a propulsion unit, means connected to said propulsion unit and adapted to be attached to the transom of a boat for affording vertical swinging movement of said propulsion unit relative to the transom about a horizontal tilt axis and for affording steering movement of said propulsion unit relative to the transom about a steering axis extending transversely of said tilt axis, said propulsion unit comprising a lower unit including an exhaust gas discharge outlet normally located underwater, a powerhead rigidly fixed to the top of said lower unit and including an engine with a plurality of combustion chambers each including an exhaust port with the lowermost of said exhaust ports being located adjacent to or below the at-reast water level when the outboard motor is boat mounted, an exhaust gas passageway communicating between said exhaust ports and said exhaust gas discharge outlet and including valveless means upstream of said exhaust gas discharge outlet for preventing entry of water through said passageway and said ports into said combustion chambers, and a water guard extending upwardly from the bottom of said powerhead in watertight encircling relation to said powerhead to above the at-rest water level when the outboard motor is boat mounted.

7. An outboard motor comprising a propulsion unit including a lower unit including an exhaust gas discharge outlet normally located underwater and a propeller normally located at least partially in the water, said propulsion unit also including a power head rigidly fixed to the top of said lower unit and including an engine having an exhaust port, said propulsion unit also including an exhaust gas discharge system communicating between said exhaust port and said exhaust gas discharge outlet and including valveless means upstream of said exhaust gas discharge outlet for preventing entry of water through said exhaust gas discharge system into said engine, a bracket adapted to be attached to the transom of a boat, a king pin having upper and lower ends, means connecting said king pin to said bracket to afford vertical swinging movement of said king pin relative to the transom about a horizontal tilt axis, means connecting said king pin upper end to said powerhead, and means connecting said king pin lower end to said lower unit, said means connecting said king pin to said engine, to said lower unit, and to said bracket affording steering movement of said propulsion unit relative to the transom about a steering axis extending transversely of said tilt axis.

8. An outboard motor in accordance with claim 7 wherein said powerhead further includes an upwardly open water guard extending from the bottom of said powerhead in watertight encircling relation to said engine to above the at-rest water level when the outboard motor is boat mounted, and wherein said means connecting said king pin upper end to said powerhead includes a member extending through an opening in said guard.

9. An outboard motor in accordance with claim 8 and further including a water tight seal extending between said member and said opening in said guard. 

1. An outboard motor comprising a propulsion unit, means connected to said propulsion unit and adapted to be attached to the transom of a boat for affording vertical swinging movement of said propulsion unit relative to the transom about a horizontal tilt axis and for affording steering movement of said propulsion unit relative to the transom about a steering axis extending transversely of said tilt axis, said propulsion unit comprising a lower unit including an exhaust gas discharge outlet normally located underwater, a powerhead assembly rigidly fixed to the top of said lower unit and including an engine with a plurality of vertically in-line cylinders each including an exhaust port, and an exhaust gas discharge system including an inverted ''''U'''' shaped passageway comprising an upper junction portion located above the at-rest water level when the outboard motor is boat mounted, a first leg extending downwardly from said junction portion and communicating with at least one of said exhaust ports, and a second leg extending downwardly fRom said junction portion and separately from said first leg and communicating with said lower unit underwater exhaust gas discharge outlet.
 2. An outboard motor comprising a transom bracket adapted to be attached to the transom of a boat, a swivel bracket adapted to be connected to said transom bracket for vertical swinging movement about a horizontal tilt axis, a propulsion unit connected to said swivel bracket for common vertical swinging movement relative to said transom bracket and for steering movement relative to said swivel bracket about a steering axis extending transversely of said tilt axis, said propulsion unit comprising a lower unit including an exhaust gas discharge outlet normally located underwater, a powerhead rigidly fixed to the top of said lower unit and including an engine with a plurality of vertically in-line cylinders each including an exhaust port and with the lowermost of said exhaust ports being located adjacent to or below the at-rest water level when the outboard motor is boat mounted, a water guard extending upwardly from the bottom of said powerhead in watertight encircling relation to said powerhead to above the at-rest water level when the outboard motor is boat mounted, and an exhaust gas discharge system including an inverted ''''U'''' shaped passageway comprising an upper junction portion located above the at-rest water level when the outboard motor is boat mounted, a first leg extending downwardly from said junction portion and communicating with at least one of said exhaust ports, and a second leg extending downwardly from said junction separately from said first leg and communicating with said lower unit underwater exhaust gas discharge outlet.
 3. An outboard motor comprising a propulsion unit, means connected to said propulsion unit and adapted to be attached to the transom of a boat for affording vertical swinging movement of said propulsion unit relative to the transom about a horizontal tilt axis and for affording steering movement of said propulsion unit relative to the transom about a steering axis extending transversely of said tilt axis, said propulsion unit comprising a lower unit including an exhaust gas discharge outlet normally located underwater, a powerhead assembly rigidly fixed to the top of said lower unit and including an engine with a plurality of combustion chambers each including an exhaust port, and an exhaust gas discharge system communicating between said exhaust ports and said exhaust gas discharge outlet and including an inverted U-shaped portion preventing entry of water through said exhaust gas discharge system into said combustion chambers under normal conditions.
 4. An outboard motor comprising a propulsion unit, means connected to said propulsion unit and adapted to be attached to the transom of a boat for affording vertical swinging movement of said propulsion unit relative to the transom about a horizontal tilt axis and for affording steering movement of said propulsion unit relative to the transom about a steering axis extending transversely of said tilt axis, said propulsion unit comprising a lower unit including an exhaust gas discharge outlet normally located underwater, a powerhead assembly rigidly fixed to the top of said lower unit and including an engine with a plurality of combustion chambers each including an exhaust port, and an exhaust gas discharge system communicating between said exhaust ports and said exhaust gas discharge outlet and including valveless means located upstream of said exhaust gas discharge outlet for preventing entry of water through said exhaust gas discharge system into said combustion chambers.
 5. An outboard motor comprising a propulsion unit, means connected to said propulsion unit and adapted to be attached to the transom of a boat for affording vertical swinging movement of said propulsion unit relative to the transom about a horizontal tilt axis and for affording steering movement of said propulsion unit relative to the transom about a steEring axis extending transversely of said tilt axis, said propulsion unit comprising a lower unit including an exhaust gas discharge outlet normally located underwater, a powerhead rigidly fixed to the top of said lower unit and including an engine with a plurality of combustion chambers each including an exhaust port with the lowermost of said exhaust ports being located adjacent to or below the at-rest water level when the outboard motor is boat mounted, an exhaust gas passageway communicating between said exhaust ports and said exhaust gas discharge outlet and including an inverted U-shaped portion preventing entry of water through said passageway and said ports into said combustion chambers, and a water guard extending upwardly from the bottom of said powerhead in watertight encircling relation to said powerhead to above the at-rest water level when the outboard motor is boat mounted.
 6. An outboard motor comprising a propulsion unit, means connected to said propulsion unit and adapted to be attached to the transom of a boat for affording vertical swinging movement of said propulsion unit relative to the transom about a horizontal tilt axis and for affording steering movement of said propulsion unit relative to the transom about a steering axis extending transversely of said tilt axis, said propulsion unit comprising a lower unit including an exhaust gas discharge outlet normally located underwater, a powerhead rigidly fixed to the top of said lower unit and including an engine with a plurality of combustion chambers each including an exhaust port with the lowermost of said exhaust ports being located adjacent to or below the at-reast water level when the outboard motor is boat mounted, an exhaust gas passageway communicating between said exhaust ports and said exhaust gas discharge outlet and including valveless means upstream of said exhaust gas discharge outlet for preventing entry of water through said passageway and said ports into said combustion chambers, and a water guard extending upwardly from the bottom of said powerhead in watertight encircling relation to said powerhead to above the at-rest water level when the outboard motor is boat mounted.
 7. An outboard motor comprising a propulsion unit including a lower unit including an exhaust gas discharge outlet normally located underwater and a propeller normally located at least partially in the water, said propulsion unit also including a power head rigidly fixed to the top of said lower unit and including an engine having an exhaust port, said propulsion unit also including an exhaust gas discharge system communicating between said exhaust port and said exhaust gas discharge outlet and including valveless means upstream of said exhaust gas discharge outlet for preventing entry of water through said exhaust gas discharge system into said engine, a bracket adapted to be attached to the transom of a boat, a king pin having upper and lower ends, means connecting said king pin to said bracket to afford vertical swinging movement of said king pin relative to the transom about a horizontal tilt axis, means connecting said king pin upper end to said powerhead, and means connecting said king pin lower end to said lower unit, said means connecting said king pin to said engine, to said lower unit, and to said bracket affording steering movement of said propulsion unit relative to the transom about a steering axis extending transversely of said tilt axis.
 8. An outboard motor in accordance with claim 7 wherein said powerhead further includes an upwardly open water guard extending from the bottom of said powerhead in watertight encircling relation to said engine to above the at-rest water level when the outboard motor is boat mounted, and wherein said means connecting said king pin upper end to said powerhead includes a member extending through an opening in said guard.
 9. An outboard motor in accordance with claim 8 and further including a water tight seal extending between said member and said openinG in said guard. 